I have had to fool with a lot of these over the years... they can get nasty.
Most have been broken off and damaged and
have been a nightmare to repair especially on a concrete floor.....
If your flange is still in good shape and not broken,
Just use 3 wax rings and sort of mold them or stack them together to
build a good seal to encompass the flange....
BE CAREFUL not to overtighten the bolts
especially on the side of the flange that only gives you two measly tits sticking out of the
wall of the flange to secure your toilet bolt too
I suggest if all goes well to go out and buy a tube of
CLEAR ALEX DAP and
smear the dap along the base of the toilet and push it underneath the base
with your finger... use a liberal amount of DAP and get it well under the toilet base
It wipes off easily with a wet sponge or rag..... and it will set up solid in a day or two
and the toilet will be firmly secured to the floor....
..and will never move again in our lifetimes
Here is a picture from my last battle with one of these broken offset flanges
I was able to burn out---basically carve out--- the inside lip of the
broken flange with a ---red hot wood chisel--- to enlarge the hole and get the
new repair flange to slide down into the pipe and then glue it in solid
This is the best repair flange made on the market today.....is slides down into
the 3 inch pipe and you just glue it in and then you win.....
It did offset the toilet slightly from center but it was still all hidden under
the toilet and it was the only way to win the battle that day without tearing up
the concrete floor and destroying the bathrooms....... and it worked fine..